This invention especially relates to improvements in the production of HCFO-1233zd(E), HCFO-1233zd(Z), HFO-1234ze(E), and HFO-1234ze (Z). As used herein, the designations 1233zd and 1234ze will be used when either the E or Z isomers, or a combination thereof, is being referred to.
These compounds have zero or low ozone depletion potential as well as low global warming potential such that they are useful and desirable as replacements for existing materials used in refrigeration, foam blowing, solvents, monomers and other applications where other fluorocarbons are currently utilized.
Methods to produce 1233zd are known in the art. See for example US Patent Publication Nos. 2012-0172636; 2012-0271069; and 2012-0271070, which describe both 1233zd and 1234ze production processes. These documents are hereby incorporated herein by reference.
A preferred embodiment for the manufacture of 1233zd is as follows:HCC-240fa+3HF→1233zd+4HClwhich takes place in a liquid or vapor phase reaction in the absence or presence of a catalyst with large excess of HF.
Methods to produce 1234ze have also been disclosed. See for example U.S. Pat. Nos. 7,485,760 and 7,638,660 where the manufacture of 1234ze is disclosed as follows:HFC-245fa→1234ze+HFwhich takes place in the liquid or vapor phase in the presence or absence of a dehydrofluorination catalyst. These patents are hereby incorporated herein by reference.
In the above processes to produce 1233zd and/or 1234ze, the crude product is usually a mixture of both the Z and E isomers (also known as the cis and trans isomers respectively). Typical processes employ one or more purification methods, such as distillation, extraction, decantation and absorption for purifying and recovering the desired fluorolefin product. Since the reaction products include the acids HCl and HF depending on the process, there is a need to remove these acid components during the product purification and recovery process. Although the bulk removal of the acids is done by one or more purification techniques such as distillation, extraction, and/or decantation; one additional unit operation that is often used for the removal of residual acidity is absorption via strong caustic solutions, such as KOH, NaOH, or the like, at a pH of about 11 or higher.
Methods to produce 3,3,3-trifluoropropyne are also known in the art. See for example U.S. Pat. No. 7,964,759, which is hereby incorporated herein by reference. Disclosed in this patent is a method to produce 3,3,3-trifluoropropyne by contacting (Z)-1-halogeno-3,3,3-trifluoropropene with a high concentration of an organic or inorganic strong base (pH>10). Both 1233zd and 1234ze are 1-halogeno-3,3,3-trifluoropropenes; 1233zd is 1-chloro-3,3,3-trifluoropropene and 1234ze is 1-fluoro-3,3,3-tetrafluoropropene.
As stated above, 3,3,3-trifluoropropyne can be formed when compounds such as 1233zd and 1234ze are allowed to react with strong bases. In processes where the desired product is one of those listed above, trifluoropropyne is usually considered to be an undesired impurity due to both potential toxicity and flammability concerns and accordingly, this compound is preferably removed if it is formed. The need for the removal of trifluoropropyne necessarily increases capital investment as well as operational costs associated with production of one or more of the above compounds. Therefore, it would be much more desirable to not form trifluoropropyne in the first place. Hence, there is a need for means by which the formation of trifluoropropyne can be avoided.
This invention provides a solution to this problem.